Optical imaging lens and electronic device comprising the same

ABSTRACT

An optical imaging lens includes: a first, second, third and fourth lens element, the first lens element has negative refractive power, the second lens element has an image-side surface with a concave part in a vicinity of the optical axis, the third lens element has positive refractive power, and has an object-side surface with a convex part in a vicinity of the optical axis, the fourth lens element has an image-side surface with a concave part in a vicinity of the optical axis, where the optical imaging lens set does not include any lens element with refractive power other than said first, second, third and fourth lens elements.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from P.R.C. Patent Application No.201410582232.2, filed on Oct. 24, 2014, the contents of which are herebyincorporated by reference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an optical imaging lens setand an electronic device which includes such optical imaging lens set.Specifically speaking, the present invention is directed to a shorteroptical imaging lens set of four lens elements and a shorter electronicdevice which includes such optical imaging lens set of four lenselements.

2. Description of the Prior Art

In recent years, the popularity of mobile phones and digital camerasmakes the sizes of various portable electronic products reduce quickly,and so does that of the photography modules. The current trend ofresearch is to develop an optical imaging lens set of a shorter lengthwith uncompromised good quality. The most important characters of anoptical imaging lens set are image quality and size.

The designing of the optical lens is not only just scaling down theoptical lens which has good optical performance, but also needs toconsider the material characteristics and satisfying some requirementslike assembly yield.

Therefore, how to reduce the total length of a photographic device, butstill maintain good optical performance, is an important researchobjective.

SUMMARY OF THE INVENTION

In light of the above, the present invention proposes an optical imaginglens set that is lightweight, has a low production cost, has an enlargedhalf of field of view, has a high resolution and has high image quality.The optical imaging lens set of four lens elements of the presentinvention has a first lens element, a second lens element, a third lenselement and a fourth lens element sequentially from an object side to animage side along an optical axis.

An optical imaging lens includes: a first, second, third and fourth lenselement, where the first lens element has negative refractive power, thesecond lens element has an image-side surface with a concave part in avicinity of the optical axis, the third lens element has positiverefractive power, and has an object-side surface with a convex part in avicinity of the optical axis, the fourth lens element has an image-sidesurface with a concave part in a vicinity of the optical axis, whereinthe optical imaging lens set does not include any lens element withrefractive power other than said first, second, third and fourth lenselements.

In the optical imaging lens set of four lens elements of the presentinvention, an air gap G12 along the optical axis is disposed between thefirst lens element and the second lens element, an air gap G23 along theoptical axis is disposed between the second lens element and the thirdlens element, an air gap G34 along the optical axis is disposed betweenthe third lens element and the fourth lens element, and the sum of totalthree air gaps between adjacent lens elements from the first lenselement to the fourth lens element along the optical axis is AAG,AAG=G12+G23+G34.

In the optical imaging lens set of four lens elements of the presentinvention, the first lens element has a first lens element thickness T1along the optical axis, the second lens element has a second lenselement thickness T2 along the optical axis, the third lens element hasa third lens element thickness T3 along the optical axis, the fourthlens element has a fourth lens element thickness T4 along the opticalaxis, and the total thickness of all the lens elements in the opticalimaging lens set along the optical axis is ALT, ALT=T1+T2+T3+T4.

Besides, the distance between an object-side surface of the first lenselement to an image plane is TTL, the effective focal length of theoptical imaging lens set is EFL, the distance between the image-sidesurface of the fourth lens element to an image plane along the opticalaxis is BFL (back focal length).

In addition, further defining: The focal length of the first lenselement is f1; The focal length of the second lens element is f2; Thefocal length of the third lens element is f3; The focal length of thefourth lens element is f4; The refractive index of the first lenselement is n1; The refractive index of the second lens element is n2;The refractive index of the third lens element is n3; The refractiveindex of the fourth lens element is n4; The Abbe number of the firstlens element is ν1; The Abbe number of the second lens element is ν2;The Abbe number of the third lens element is ν3; The Abbe number of thefourth lens element is ν4.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship EFL/BFL≦2.35 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/AAG≦13.94 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/G12≦89.82 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/T2≦32.35 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship ALT/G23≦47.81 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/G23≦71.93 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship ALT/G34≦40.80 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/G34≦61.66 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/T1≦17.06 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship ALT/T2≦20.82 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/T3≦12.87 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship |ν1−ν2|≦10 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/T4≦21.49 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship TTL/BFL≦5.77 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship |ν2−ν3|≦10 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship ALT/AAG≦9.22 is satisfied.

In the optical imaging lens set of four lens elements of the presentinvention, the relationship T3/T4≦4.34 is satisfied.

The present invention also proposes an electronic device which includesthe optical imaging lens set as described above. The electronic deviceincludes a case and an image module disposed in the case. The imagemodule includes an optical imaging lens set as described above, a barrelfor the installation of the optical imaging lens set, a module housingunit for the installation of the barrel, a substrate for theinstallation of the module housing unit, and an image sensor disposed onthe substrate and at an image side of the optical imaging lens set.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 illustrates the methods for determining the surface shapes andfor determining one region is a region in a vicinity of the optical axisor the region in a vicinity of its circular periphery of one lenselement.

FIG. 6 illustrates a first example of the optical imaging lens set ofthe present invention.

FIG. 7A illustrates the longitudinal spherical aberration on the imageplane of the first example.

FIG. 7B illustrates the astigmatic aberration on the sagittal directionof the first example.

FIG. 7C illustrates the astigmatic aberration on the tangentialdirection of the first example.

FIG. 7D illustrates the distortion aberration of the first example.

FIG. 8 illustrates a second example of the optical imaging lens set offour lens elements of the present invention.

FIG. 9A illustrates the longitudinal spherical aberration on the imageplane of the second example.

FIG. 9B illustrates the astigmatic aberration on the sagittal directionof the second example.

FIG. 9C illustrates the astigmatic aberration on the tangentialdirection of the second example.

FIG. 9D illustrates the distortion aberration of the second example.

FIG. 10 illustrates a third example of the optical imaging lens set offour lens elements of the present invention.

FIG. 11A illustrates the longitudinal spherical aberration on the imageplane of the third example.

FIG. 11B illustrates the astigmatic aberration on the sagittal directionof the third example.

FIG. 11C illustrates the astigmatic aberration on the tangentialdirection of the third example.

FIG. 11D illustrates the distortion aberration of the third example.

FIG. 12 illustrates a fourth example of the optical imaging lens set offour lens elements of the present invention.

FIG. 13A illustrates the longitudinal spherical aberration on the imageplane of the fourth example.

FIG. 13B illustrates the astigmatic aberration on the sagittal directionof the fourth example.

FIG. 13C illustrates the astigmatic aberration on the tangentialdirection of the fourth example.

FIG. 13D illustrates the distortion aberration of the fourth example.

FIG. 14 illustrates a fifth example of the optical imaging lens set offour lens elements of the present invention.

FIG. 15A illustrates the longitudinal spherical aberration on the imageplane of the fifth example.

FIG. 15B illustrates the astigmatic aberration on the sagittal directionof the fifth example.

FIG. 15C illustrates the astigmatic aberration on the tangentialdirection of the fifth example.

FIG. 15D illustrates the distortion aberration of the fifth example.

FIG. 16 illustrates a sixth example of the optical imaging lens set offour lens elements of the present invention.

FIG. 17A illustrates the longitudinal spherical aberration on the imageplane of the sixth example.

FIG. 17B illustrates the astigmatic aberration on the sagittal directionof the sixth example.

FIG. 17C illustrates the astigmatic aberration on the tangentialdirection of the sixth example.

FIG. 17D illustrates the distortion aberration of the sixth example.

FIG. 18 illustrates a seventh example of the optical imaging lens set offour lens elements of the present invention.

FIG. 19A illustrates the longitudinal spherical aberration on the imageplane of the seventh example.

FIG. 19B illustrates the astigmatic aberration on the sagittal directionof the seventh example.

FIG. 19C illustrates the astigmatic aberration on the tangentialdirection of the seventh example.

FIG. 19D illustrates the distortion aberration of the seventh example.

FIG. 20 illustrates an eighth example of the optical imaging lens set offour lens elements of the present invention.

FIG. 21A illustrates the longitudinal spherical aberration on the imageplane of the eighth example.

FIG. 21B illustrates the astigmatic aberration on the sagittal directionof the eighth example.

FIG. 21C illustrates the astigmatic aberration on the tangentialdirection of the eighth example.

FIG. 21D illustrates the distortion aberration of the eighth example.

FIG. 22 illustrates an ninth example of the optical imaging lens set offour lens elements of the present invention.

FIG. 23A illustrates the longitudinal spherical aberration on the imageplane of the ninth example.

FIG. 23B illustrates the astigmatic aberration on the sagittal directionof the ninth example.

FIG. 23C illustrates the astigmatic aberration on the tangentialdirection of the ninth example.

FIG. 23D illustrates the distortion aberration of the ninth example.

FIG. 24 illustrates a first preferred example of the portable electronicdevice with an optical imaging lens set of the present invention.

FIG. 25 illustrates a second preferred example of the portableelectronic device with an optical imaging lens set of the presentinvention.

FIG. 26 shows the optical data of the first example of the opticalimaging lens set.

FIG. 27 shows the aspheric surface data of the first example.

FIG. 28 shows the optical data of the second example of the opticalimaging lens set.

FIG. 29 shows the aspheric surface data of the second example.

FIG. 30 shows the optical data of the third example of the opticalimaging lens set.

FIG. 31 shows the aspheric surface data of the third example.

FIG. 32 shows the optical data of the fourth example of the opticalimaging lens set.

FIG. 33 shows the aspheric surface data of the fourth example.

FIG. 34 shows the optical data of the fifth example of the opticalimaging lens set.

FIG. 35 shows the aspheric surface data of the fifth example.

FIG. 36 shows the optical data of the sixth example of the opticalimaging lens set.

FIG. 37 shows the aspheric surface data of the sixth example.

FIG. 38 shows the optical data of the seventh example of the opticalimaging lens set.

FIG. 39 shows the aspheric surface data of the seventh example.

FIG. 40 shows the optical data of the eighth example of the opticalimaging lens set.

FIG. 41 shows the aspheric surface data of the eighth example.

FIG. 42 shows the optical data of the ninth example of the opticalimaging lens set.

FIG. 43 shows the aspheric surface data of the ninth example.

FIG. 44 shows some important ratios in the examples.

DETAILED DESCRIPTION

Before the detailed description of the present invention, the firstthing to be noticed is that in the present invention, similar (notnecessarily identical) elements are labeled as the same numeralreferences. In the entire present specification, “a certain lens elementhas negative/positive refractive power” refers to the negative/positiverefractive power of the lens element on the optical axis calculated byGaussian optical theory. An object-side/image-side surface refers to theregion which allows imaging light passing through, in the drawing,imaging light includes Lc (chief ray) and Lm (marginal ray). As shown inFIG. 1, the optical axis is “I” and the lens element is symmetrical withrespect to the optical axis I. The region A that around the optical axisand for light to pass through is the region in a vicinity of the opticalaxis, and the region C that the marginal ray passing through is theregion in a vicinity of a certain lens element's circular periphery. Inaddition, the lens element may include an extension part E for the lenselement to be installed in an optical imaging lens set (that is theregion outside the region C perpendicular to the optical axis). Ideallyspeaking, no light would pass through the extension part, and the actualstructure and shape of the extension part is not limited to this and mayhave other variations. For the reason of simplicity, some of theextension part is not illustrated in the following examples. More,precisely, the method for determining the surface shapes or the regionin a vicinity of the optical axis, the region in a vicinity of itscircular periphery and other regions is described in followingparagraph:

1. Please refer to FIG. 1, which is a cross section viewed lens elementstructure along the optical axis. As shown in cross section views, whendetermining the regions of the lens element, a middle point is definedas the intersection of the optical axis and the lens element's surface,and a conversion point is a point disposed on the surface of the lenselement, the tangent of the conversion point is perpendicular to theoptical axis. If there are more than one conversion points on the lenselement, these conversion points are labeled as the first conversionpoint, the second conversion points . . . to the nth conversion pointfrom the optical axis to outwardly. The region that is between themiddle point and the first conversion point is the region in a vicinityof the optical axis, and the region outside the nth conversion point isthe region in a vicinity of its circular periphery. And the otherregions therebetween can be defined as different regions according tothe conversion point. In addition, the optical effective radius refersto the perpendicular distance between the intersection of the marginalray Lm and the surface of the lens element and the optical axis I.

2. As shown in FIG. 2, judging one region is a convex part or a concavepart depends on the intersection of a parallel emitted light (or theextending line of the light) and the optical axis is disposed on theobject side or disposed on the image side, the method mentioned above isalso called light focusing method. For example, when the light passesthrough one region and focuses on the image-side, the intersection ofthe light and the optical axis is disposed on the image-side, such asthe point R shown in FIG. 2, therefore, the region is a convex part. Onthe other hand, if the light passes through one region and the light isscattered, the intersection of the extending line of the light and theoptical axis is disposed on the object-side, such as the point M shownin FIG. 2, therefore the region is a concave part. As shown in FIG. 2,the region between the optical axis and the first conversion point is aconvex part, and the region outside the first conversion point is aconcave part. It can be understood that the first conversion point isthe demarcation point from the convex part to the concave part. Besides,the value R (refers to the radius of curvature, usually shown in lensdata) can also determine the shapes of the region in vicinity of theoptical axis. On the object-side, if the value R is positive, then theregion is a convex part; if the value R is negative, then the region isa concave part. On the image-side, if the value R is positive, then theregion is a concave part; if the value R is negative, then the region isa convex part. The method mentioned above can also determine the shapesof the region in vicinity of the optical axis and the result is the samewith that judged by the light focusing method.

3. If there is not any conversion point on the surface of the lenselement, the 0-50% optical effective radius is defined as the region ina vicinity of the optical axis, and the 50-100% optical effective radiusis defined as the region in a vicinity of its circular periphery.

FIG. 3 is an example showing the lens element only having the firstconversion point on the surface of the lens element, so the first regionis a region in vicinity of the optical axis, and the second region is aregion in vicinity of its circular periphery. The lens element haspositive value R on the image-side, so the region in a vicinity of theoptical axis is a concave part; since a conversion point is disposedbetween the first region and the second region, the shapes of the regionin a vicinity of its circular periphery (the second region) aredifferent from the shape of the region (the first region) that is nearit. In other words, the shapes of the region in a vicinity of itscircular periphery are different from the shape of the region in avicinity of the optical axis, so the region in a vicinity of itscircular periphery is a convex part.

FIG. 4 is an example showing the lens element having the firstconversion point and the second conversion point on the surface of thelens element, so the first region is a region in vicinity of the opticalaxis, and the third region is a region in vicinity of its circularperiphery. The lens element has positive value R on the object-side, sothe region in a vicinity of the optical axis is a convex part; theregion between the first conversion point and the second conversionpoint (the second region) is a concave part, so the region in a vicinityof its circular periphery (the third region) is a convex region.

FIG. 5 is an example showing the lens element having no conversion pointon the surface of the lens element, so the 0-50% optical effectiveradius is defined as the region in a vicinity of the optical axis, andthe 50-100% optical effective radius is defined as the region in avicinity of its circular periphery. The lens element has positive valueR on the object-side, so the region in a vicinity of the optical axis isa convex part, and since there is no conversion point disposed betweenthe region in vicinity of the optical axis the region in vicinity of itscircular periphery, the region in a vicinity of its periphery is aconvex part.

As shown in FIG. 6, the optical imaging lens set 1 of four lens elementsof the present invention, sequentially located from an object side 2(where an object is located) to an image side 3 along an optical axis 4,have a first lens element 10, a second lens element 20, an aperture stop80, a third lens element 30, a fourth lens element 40, a filter 72 andan image plane 71. Generally speaking, the first lens element 10, thesecond lens element 20, the third lens element 30 and the fourth lenselement 40 may be made of a transparent plastic material and each has anappropriate refractive power, but the present invention is not limitedto this. There are exclusively four lens elements with refractive powerin the optical imaging lens set 1 of the present invention. The opticalaxis 4 is the optical axis of the entire optical imaging lens set 1, andthe optical axis of each of the lens elements coincides with the opticalaxis of the optical imaging lens set 1.

Furthermore, the optical imaging lens set 1 includes an aperture stop(ape. stop) 80 disposed in an appropriate position. In FIG. 1, theaperture stop 80 is disposed between the second lens element 20 and thethird lens element 30. When light emitted or reflected by an object (notshown) which is located at the object side 2 enters the optical imaginglens set 1 of the present invention, it forms a clear and sharp image onthe image plane 71 at the image side 3 after passing through the firstlens element 10, the second lens element 20, the aperture stop 80, thethird lens element 30, the fourth lens element 40 and the filter 72.

In the embodiments of the present invention, the optional filter 72 maybe a filter of various suitable functions, for example, the filter 72may be an infrared cut filter (IR cut filter), placed between the fourthlens element 40 and the image plane 71. The filter 72 is made of glass.

Each lens element in the optical imaging lens set 1 of the presentinvention has an object-side surface facing toward the object side 2 aswell as an image-side surface facing toward the image side 3. Forexample, the first lens element 10 has a first object-side surface 11and a first image-side surface 12; the second lens element 20 has asecond object-side surface 21 and a second image-side surface 22; thethird lens element 30 has a third object-side surface 31 and a thirdimage-side surface 32; the fourth lens element 40 has a fourthobject-side surface 41 and a fourth image-side surface 42. In addition,each object-side surface and image-side surface in the optical imaginglens set 1 of the present invention has a part in a vicinity of itscircular periphery (circular periphery part) away from the optical axis4 as well as a part in a vicinity of the optical axis (optical axispart) close to the optical axis 4.

Each lens element in the optical imaging lens set 1 of the presentinvention further has a central thickness on the optical axis 4. Forexample, the first lens element 10 has a first lens element thicknessT1, the second lens element 20 has a second lens element thickness T2,the third lens element 30 has a third lens element thickness T3, thefourth lens element 40 has a fourth lens element thickness T4.Therefore, the total thickness of all the lens elements in the opticalimaging lens set 1 along the optical axis 4 is ALT, ALT=T1+T2+T3+T4.

In addition, between two adjacent lens elements in the optical imaginglens set 1 of the present invention there is an air gap along theoptical axis 4. For example, an air gap G12 is disposed between thefirst lens element 10 and the second lens element 20, an air gap G23 isdisposed between the second lens element 20 and the third lens element30, and an air gap G34 is disposed between the third lens element 30 andthe fourth lens element 40. Therefore, the sum of total three air gapsbetween adjacent lens elements from the first lens element 10 to thefourth lens element 40 along the optical axis 4 is AAG, AAG=G12+G23+G34.

In addition, the distance between the first object-side surface 11 ofthe first lens element 10 to the image plane 71, namely the total lengthof the optical imaging lens set along the optical axis 4 is TTL; theeffective focal length of the optical imaging lens set is EFL; thedistance between the fourth image-side surface 42 of the four lenselement 40 to the image plane 71 along the optical axis 4 is BFL; thedistance between the fourth image-side surface 42 of the four lenselement 40 to the filter 72 along the optical axis 4 is G4F; thethickness of the filter 72 along the optical axis 4 is TF; the distancebetween the filter 72 to the image plane 71 along the optical axis 4 isGFP; Therefore, BFL=G4F+TF+GFP.

Furthermore, the focal length of the first lens element 10 is f1; thefocal length of the second lens element 20 is f2; the focal length ofthe third lens element 30 is f3; the focal length of the fourth lenselement 40 is f4; the refractive index of the first lens element 10 isn1; the refractive index of the second lens element 20 is n2; therefractive index of the third lens element 30 is n3; the refractiveindex of the fourth lens element 40 is n4; the Abbe number of the firstlens element 10 is ν1; the Abbe number of the second lens element 20 isν2; the Abbe number of the third lens element 30 is ν3; and the Abbenumber of the fourth lens element 40 is ν4.

First Example

Please refer to FIG. 6 which illustrates the first example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 7A for the longitudinal spherical aberration on the image plane 71of the first example; please refer to FIG. 7B for the astigmatic fieldaberration on the sagittal direction; please refer to FIG. 7C for theastigmatic field aberration on the tangential direction, and pleaserefer to FIG. 7D for the distortion aberration. The Y axis of thespherical aberration in each example is “field of view” for 1.0. The Yaxis of the astigmatic field and the distortion in each example standfor image height. The image height is 1.78 mm.

The optical imaging lens set 1 of the first example has four lenselements 10 to 40 made of a plastic material and having refractivepower. The optical imaging lens set 1 also has an aperture stop 80, afilter 72, and an image plane 71. The aperture stop 80 is providedbetween the second lens element 20 and the third lens element 30. Thefilter 72 may be used for preventing specific wavelength light (such asthe infrared light) from reaching the image plane to adversely affectthe imaging quality.

The first lens element 10 has negative refractive power. The firstobject-side surface 11 facing toward the object side 2 is a convexsurface, having a convex part 13 in the vicinity of the optical axis anda convex part 14 in a vicinity of its circular periphery. The firstimage-side surface 12 facing toward the image side 3 is a concavesurface, having a concave part 16 in the vicinity of the optical axisand a concave part 17 in a vicinity of its circular periphery. Besides,both the first object-side surface 11 and the first image-side 12 of thefirst lens element 10 are aspherical surfaces.

The second lens element 20 has positive refractive power. The secondobject-side surface 21 facing toward the object side 2 has a convex part23 in the vicinity of the optical axis and a convex part 24 in avicinity of its circular periphery. The second image-side surface 22facing toward the image side 3 is a concave surface, having a concavepart 26 in the vicinity of the optical axis and a concave part 27 in avicinity of its circular periphery. Both the second object-side surface21 and the second image-side 22 of the second lens element 20 areaspherical surfaces.

The third lens element 30 has positive refractive power. The thirdobject-side surface 31 facing toward the object side 2 has a convex part33 in the vicinity of the optical axis and a convex part 34 in avicinity of its circular periphery. The third image-side surface 32facing toward the image side 3 is a convex surface, having a convex part36 in the vicinity of the optical axis and a convex part 37 in avicinity of its circular periphery. Both the third object-side surface31 and the third image-side 32 of the third lens element 30 areaspherical surfaces.

The fourth lens element 40 has positive refractive power. The fourthobject-side surface 41 facing toward the object side 2 has a convex part43 in the vicinity of the optical axis and a concave part 44 in avicinity of its circular periphery; The fourth image-side surface 42facing toward the image side 3 has a concave part 46 in the vicinity ofthe optical axis and a convex part 47 in a vicinity of its circularperiphery. Both the fourth object-side surface 41 and the fourthimage-side 42 of the fourth lens element 40 are aspherical surfaces. Thefilter 72 may be disposed between the fourth lens element 40 and theimage plane 71.

In the optical imaging lens element 1 of the present invention, theobject-side surfaces 11/21/31/41 and image-side surfaces 12/22/32/42 areall aspherical. These aspheric coefficients are defined according to thefollowing formula:

${Z(Y)} = {{\frac{Y^{2}}{R}/( {1 + \sqrt{1 - {( {1 + K} )\frac{Y^{2}}{R^{2}}}}} )} + {\sum\limits_{i = 1}^{n}{a_{2i} \times Y^{2i}}}}$

In which:

R represents the curvature radius of the lens element surface;

Z represents the depth of an aspherical surface (the perpendiculardistance between the point of the aspherical surface at a distance Yfrom the optical axis and the tangent plane of the vertex on the opticalaxis of the aspherical surface);

Y represents a vertical distance from a point on the aspherical surfaceto the optical axis;

K is a conic constant; and

a2i is the aspheric coefficient of the 2i order.

The optical data of the first example of the optical imaging lens set 1are shown in FIG. 26 while the aspheric surface data are shown in FIG.27. In the present examples of the optical imaging lens set, thef-number of the entire optical lens element system is Fno, HFOV standsfor the half field of view which is half of the field of view of theentire optical lens element system, and the unit for the curvatureradius, the thickness and the focal length is in millimeters (mm). Thelength of the optical imaging lens set (the distance from the firstobject-side surface 11 of the first lens element 10 to the image plane71) is 4.00 mm. HFOV is 46 degrees, and the image height is 1.78 mm.Some important ratios of the first example are shown in FIG. 44.

Second Example

Please refer to FIG. 8 which illustrates the second example of theoptical imaging lens set 1 of the present invention. It is noted thatcomparing the second example to the following examples, in order tosimplify the figures, only the components different from what the firstexample has and the basic lens elements will be labeled in figures.Other components that are the same as what the first example has, suchas the object-side surface, the image-side surface, the part in avicinity of the optical axis and the part in a vicinity of its circularperiphery will be omitted in the following example. Please refer to FIG.9A for the longitudinal spherical aberration on the image plane 71 ofthe second example; please refer to FIG. 9B for the astigmaticaberration on the sagittal direction; please refer to FIG. 9C for theastigmatic aberration on the tangential direction, and please refer toFIG. 9D for the distortion aberration. The components in the secondexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example.The optical data of the second example of the optical imaging lens setare shown in FIG. 28 while the aspheric surface data are shown in FIG.29. The length of the optical imaging lens set is 3.97 mm. HFOV is 46degrees, and the image height is 1.78 mm. Some important ratios of thesecond example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having shorter total length, having betterimaging quality, being easier to produce and having higher yield.

Third Example

Please refer to FIG. 10 which illustrates the third example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 11A for the longitudinal spherical aberration on the image plane 71of the third example; please refer to FIG. 11B for the astigmaticaberration on the sagittal direction; please refer to FIG. 11C for theastigmatic aberration on the tangential direction, and please refer toFIG. 11D for the distortion aberration. The components in the thirdexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example.The optical data of the third example of the optical imaging lens setare shown in FIG. 30 while the aspheric surface data are shown in FIG.31. The length of the optical imaging lens set is 3.96 mm. HFOV is 46degrees, and the image height is 1.77 mm. Some important ratios of thethird example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having shorter total length, being easier toproduce and having higher yield.

Fourth Example

Please refer to FIG. 12 which illustrates the fourth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 13A for the longitudinal spherical aberration on the image plane 71of the fourth example; please refer to FIG. 13B for the astigmaticaberration on the sagittal direction; please refer to FIG. 13C for theastigmatic aberration on the tangential direction, and please refer toFIG. 13D for the distortion aberration. The components in the fourthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the second lens element 20 has negative refractivepower. The optical data of the fourth example of the optical imaginglens set are shown in FIG. 32 while the aspheric surface data are shownin FIG. 33. The length of the optical imaging lens set is 4.48 mm. HFOVis 46 degrees, and the image height is 1.77 mm. Some important ratios ofthe fourth example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as being easier to produce and having higher yield.

Fifth Example

Please refer to FIG. 14 which illustrates the fifth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 15A for the longitudinal spherical aberration on the image plane 71of the fifth example; please refer to FIG. 15B for the astigmaticaberration on the sagittal direction; please refer to FIG. 15C for theastigmatic aberration on the tangential direction, and please refer toFIG. 15D for the distortion aberration. The components in the fifthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example.The optical data of the fifth example of the optical imaging lens setare shown in FIG. 34 while the aspheric surface data are shown in FIG.35. The length of the optical imaging lens set is 3.79 mm. HFOV is 46degrees, and the image height is 1.52 mm. Some important ratios of thefifth example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having shorter total length, having betterimaging quality, being easier to produce and having higher yield.

Sixth Example

Please refer to FIG. 16 which illustrates the sixth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 17A for the longitudinal spherical aberration on the image plane 71of the sixth example; please refer to FIG. 17B for the astigmaticaberration on the sagittal direction; please refer to FIG. 17C for theastigmatic aberration on the tangential direction, and please refer toFIG. 17D for the distortion aberration. The components in the sixthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the second lens element 20 has negative refractivepower. The optical data of the sixth example of the optical imaging lensset are shown in FIG. 36 while the aspheric surface data are shown inFIG. 37. The length of the optical imaging lens set is 5.63 mm. HFOV is46 degrees, and the image height is 1.71 mm. Some important ratios ofthe fifth example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having better imaging quality, being easier toproduce and having higher yield.

Seventh Example

Please refer to FIG. 18 which illustrates the seventh example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 19A for the longitudinal spherical aberration on the image plane 71of the seventh example; please refer to FIG. 19B for the astigmaticaberration on the sagittal direction; please refer to FIG. 19C for theastigmatic aberration on the tangential direction, and please refer toFIG. 19D for the distortion aberration. The components in the seventhexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example.The optical data of the seventh example of the optical imaging lens setare shown in FIG. 38 while the aspheric surface data are shown in FIG.39. The length of the optical imaging lens set is 3.10 mm. HFOV is 46degrees, and the image height is 1.44 mm. Some important ratios of thefifth example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having shorter total length, having betterimaging quality, being easier to produce and having higher yield.

Eighth Example

Please refer to FIG. 20 which illustrates the eighth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 21A for the longitudinal spherical aberration on the image plane 71of the eighth example; please refer to FIG. 21B for the astigmaticaberration on the sagittal direction; please refer to FIG. 21C for theastigmatic aberration on the tangential direction, and please refer toFIG. 21D for the distortion aberration. The components in the eighthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example.The optical data of the eighth example of the optical imaging lens setare shown in FIG. 40 while the aspheric surface data are shown in FIG.41. The length of the optical imaging lens set is 4.64 mm. HFOV is 46degrees, and the image height is 1.70 mm. Some important ratios of thefifth example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having better imaging quality, being easier toproduce and having higher yield.

Ninth Example

Please refer to FIG. 22 which illustrates the ninth example of theoptical imaging lens set 1 of the present invention. Please refer toFIG. 23A for the longitudinal spherical aberration on the image plane 71of the ninth example; please refer to FIG. 23B for the astigmaticaberration on the sagittal direction; please refer to FIG. 23C for theastigmatic aberration on the tangential direction, and please refer toFIG. 23D for the distortion aberration. The components in the ninthexample are similar to those in the first example, but the optical datasuch as the curvature radius, the refractive power, the lens thickness,the lens focal length, the aspheric surface or the back focal length inthis example are different from the optical data in the first example,and in this example, the second lens element 20 has negative refractivepower. The optical data of the ninth example of the optical imaging lensset are shown in FIG. 42 while the aspheric surface data are shown inFIG. 43. The length of the optical imaging lens set is 3.67 mm. HFOV is46 degrees, and the image height is 1.51 mm. Some important ratios ofthe fifth example are shown in FIG. 44.

It is worth noting, compared with the first example, this example hassome advantages such as having shorter total length, having betterimaging quality, being easier to produce and having higher yield.

Following is the definitions of each parameter mentioned above and someother parameters which are not disclosed in the examples of the presentinvention, shown as TABLE 1:

TABLE 1 Parameter Definition T1 The thickness of the first lens elementalong the optical axis G12 The distance between the first lens elementand the second lens element along the optical axis T2 The thickness ofthe second lens element along the optical axis G23 The distance betweenthe second lens element and the third lens element along the opticalaxis T3 The thickness of the third lens element along the optical axisG34 The distance between the third lens element and the fourth lenselement along the optical axis T4 The thickness of the fourth lenselement along the optical axis G4F The distance between the fourthimage-side surface of the fourth lens element to the filter along theoptical axis TF The thickness of the filter along the optical axis GFPThe distance between the filter to the image plane along the opticalaxis f1 The focal length of the first lens element f2 The focal lengthof the second lens element f3 The focal length of the third lens elementf4 The focal length of the fourth lens element n1 The refractive indexof the first lens element n2 The refractive index of the second lenselement n3 The refractive index of the third lens element n4 Therefractive index of the fourth lens element υ1 The Abbe number of thefirst lens element υ2 The Abbe number of the second lens element υ3 TheAbbe number of the third lens element υ4 The Abbe number of the fourthlens element EFL The effective focal length of the optical imaging lensset TTL The distance between the first object-side surface of the firstlens element to the image plane ALT The total thickness of all the lenselements in the optical imaging lens set along the optical axis AAG Thesum of total three air gaps between adjacent lens elements from thefirst lens element to the fourth lens element along the optical axis BFLThe distance between the image-side surface of the fourth lens elementto the image plane along the optical axis

The applicant summarized the efficacy of each embodiment mentioned aboveas follows:

In the present invention, all of the longitudinal spherical aberration,the astigmatism aberration and the distortion are in compliance with theusage standard. In addition, the off-axis light of red, blue and greenwavelengths are focused on the vicinity of the imaging point indifferent heights, therefore the deviation between each off-axis lightand the imaging point is well controlled, so as to have good suppressionfor spherical aberration, aberration and distortion. Furthermore, thecurves of red, blue and green wavelengths are very close to each other,meaning that the dispersion on the axis has greatly improved too. Insummary, the different lens elements of the present invention arematched to each other, to achieve good image quality.

In addition, the inventors discover that there are some better ratioranges for different data according to the above various importantratios, which are shown as follows. Better ratio ranges help thedesigners to design the better optical performance and an effectivelyreduced length of a practically possible optical imaging lens set.

1. If the optical imaging lens set satisfies the followingrelationships: |ν1−ν2|≦20, the optical imaging lens set will have abetter arrangement and good image performance, and further have smallervolume.

2. If the optical imaging lens set satisfies one of the followingrelationships: EFL/BFL≦2.35; TTL/AAG≦13.94; TTL/G12≦89.82; TTL/T2≦32.35;ALT/G23≦47.81; TTL/G23≦71.93; ALT/G34≦40.80; TTL/G34≦61.66;TTL/T1≦17.06; ALT/T2≦20.82; TTL/T3≦12.87; TTL/T4≦21.49; TTL/BFL≦5.77;|ν2−ν3|≦10; ALT/AAG≦9.22; T3/T4≦4.34, the total length of the opticalimaging lens set can be shrunk effectively. If further satisfying one ofthe following relationships: 0.60≦EFL/BFL≦2.35; 2.50≦TTL/AAG≦13.94;9.60≦TTL/G12≦89.82; 2.12≦TTL/T2≦32.35; 3.84≦ALT/G23≦47.81;8.27≦TTL/G23≦71.93; 2.66≦ALT/G34≦40.80; 5.72≦TTL/G34≦61.66;2.11≦TTL/T1≦17.06; 1.41≦ALT/T2≦20.82; 1.83≦TTL/T3≦12.87;2.52≦TTL/T4≦21.49; 1.74≦TTL/BFL≦5.77; 1.16≦ALT/AAG≦9.22;0.48≦T3/T4≦4.34, the optical imaging lens set will have better imagingquality.

It is worth noting that, in view of the unpredictability of the opticalsystem design, under the structure of the invention, controlling theparameters can help the designer to design the optical imaging lens setwith good optical performance, having shorter total length, and beingfeasible in manufacturing process. Each parameter has its preferredrange.

The optical imaging lens set 1 of the present invention may be appliedto an electronic device, such as mobile phones, game consoles or drivingrecorders. Please refer to FIG. 24. FIG. 24 illustrates a firstpreferred example of the optical imaging lens set 1 of the presentinvention for use in a portable electronic device 100. The electronicdevice 100 includes a case 110, and an image module 120 mounted in thecase 110. A mobile phone is illustrated in FIG. 24 as an example, butthe electronic device 100 is not limited to a mobile phone.

As shown in FIG. 24, the image module 120 includes the optical imaginglens set 1 as described above. FIG. 24 illustrates the aforementionedfirst example of the optical imaging lens set 1. In addition, theportable electronic device 100 also contains a barrel 130 for theinstallation of the optical imaging lens set 1, a module housing unit140 for the installation of the barrel 130, a substrate 172 for theinstallation of the module housing unit 140 and an image sensor 70disposed at the substrate 172, and at the image side 3 of the opticalimaging lens set 1. The image sensor 70 in the optical imaging lens set1 may be an electronic photosensitive element, such as a charge coupleddevice or a complementary metal oxide semiconductor element. The imageplane 71 forms at the image sensor 70.

The image sensor 70 used here is a product of chip on board (COB)package rather than a product of the conventional chip scale package(CSP) so it is directly attached to the substrate 172, and protectiveglass is not needed in front of the image sensor 70 in the opticalimaging lens set 1, but the present invention is not limited to this.

To be noticed in particular, the case 110, the barrel 130, and/or themodule housing unit 140 may be a single element or consist of aplurality of elements, but the present invention is not limited to this.

Each one of the four lens elements 10, 20, 30 and 40 with refractivepower is installed in the barrel 130 with air gaps disposed between twoadjacent lens elements in an exemplary way. The module housing unit 140has a lens element housing 141, and an image sensor housing 146installed between the lens element housing 141 and the image sensor 70.However in other examples, the image sensor housing 146 is optional. Thebarrel 130 is installed coaxially along with the lens element housing141 along the axis I-I′, and the barrel 130 is provided inside of thelens element housing 141.

Please also refer to FIG. 25 for another application of theaforementioned optical imaging lens set 1 in a portable electronicdevice 200 in the second preferred example. The main differences betweenthe portable electronic device 200 in the second preferred example andthe portable electronic device 100 in the first preferred example are:the lens element housing 141 has a first seat element 142, a second seatelement 143, a coil 144 and a magnetic component 145. The first seatelement 142 is for the installation of the barrel 130, exteriorlyattached to the barrel 130 and disposed along the axis I-I′. The secondseat element 143 is disposed along the axis I-I′ and surrounds theexterior of the first seat element 142. The coil 144 is provided betweenthe outside of the first seat element 142 and the inside of the secondseat element 143. The magnetic component 145 is disposed between theoutside of the coil 144 and the inside of the second seat element 143.

The first seat element 142 may pull the barrel 130 and the opticalimaging lens set 1 which is disposed inside of the barrel 130 to movealong the axis I-I′, namely the optical axis 4 in FIG. 6. The imagesensor housing 146 is attached to the second seat element 143. Otherdetails of the portable electronic device 200 in the second preferredexample are similar to those of the portable electronic device 100 inthe first preferred example so they are not elaborated again.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. An optical imaging lens set, from an object sidetoward an image side in order along an optical axis comprising: a firstlens element, a second lens element, a third lens element and a fourthlens element, said first to fourth lens elements having an object-sidesurface facing toward the object side as well as an image-side surfacefacing toward the image side, wherein: said first lens element haspositive refractive power; said second lens element has an image-sidesurface with a concave part in a vicinity of the optical axis; saidthird lens element has positive refractive power, and has an object-sidesurface with a convex part in a vicinity of the optical axis; saidfourth lens element has an image-side surface with a concave part in avicinity of the optical axis; and wherein the optical imaging lens setdoes not include any lens element with refractive power other than saidfirst, second, third and fourth lens elements.
 2. The optical imaginglens set of claim 1, wherein the effective focal length EFL of theoptical imaging lens set, and a distance BFL between the image-sidesurface of said fourth lens element to an image plane satisfy arelationship EFL/BFL≦2.35.
 3. The optical imaging lens set of claim 2,wherein a distance TTL between said object-side surface of said firstlens element to an image plane, and the sum of all three air gaps AAGbetween each lens element from said first lens element to said fourthlens element along the optical axis satisfy a relationshipTTL/AAG≦13.94.
 4. The optical imaging lens set of claim 1, furthercomprising an aperture stop disposed between said second lens elementand said third lens element.
 5. The optical imaging lens set of claim 4,wherein a distance TTL between said object-side surface of said firstlens element to an image plane, and an air gap G12 between said firstlens element and said second lens element along said optical axissatisfy a relationship TTL/G12≦89.82.
 6. The optical imaging lens set ofclaim 1, wherein a distance TTL between said object-side surface of saidfirst lens element to an image plane, and a thickness T2 of said secondlens element along said optical axis satisfy a relationshipTTL/T2≦32.35.
 7. The optical imaging lens set of claim 6, wherein atotal thickness ALT of said first lens element, said second lenselement, said third lens element and said fourth lens element along saidoptical axis, and an air gap G23 between said second lens element andsaid third lens element along said optical axis satisfy a relationshipALT/G23≦47.81.
 8. The optical imaging lens set of claim 1, wherein adistance TTL between said object-side surface of said first lens elementto an image plane, and an air gap G23 between said second lens elementand said third lens element along said optical axis satisfy arelationship TTL/G23≦71.93.
 9. The optical imaging lens set of claim 8,wherein a total thickness ALT of said first lens element, said secondlens element, said third lens element and said fourth lens element alongsaid optical axis, and an air gap G34 between said third lens elementand said fourth lens element along said optical axis satisfy arelationship ALT/G34≦40.80.
 10. The optical imaging lens set of claim 1,wherein a distance TTL between said object-side surface of said firstlens element to an image plane, and an air gap G34 between said thirdlens element and said fourth lens element along said optical axissatisfy a relationship TTL/G34≦61.66.
 11. The optical imaging lens setof claim 10, wherein a thickness T1 of said first lens element alongsaid optical axis satisfies a relationship TTL/T1≦17.06.
 12. The opticalimaging lens set of claim 1, wherein a total thickness ALT of said firstlens element, said second lens element, said third lens element and saidfourth lens element along said optical axis, and a thickness T2 of saidsecond lens element along said optical axis satisfy a relationshipALT/T2≦20.82.
 13. The optical imaging lens set of claim 12, wherein adistance TTL between said object-side surface of said first lens elementto an image plane, and a thickness T3 of said third lens element alongsaid optical axis satisfy a relationship TTL/T3≦12.87.
 14. The opticalimaging lens set of claim 1, wherein an Abbe number ν1 of said firstlens element, and an Abbe number ν2 of said second lens element satisfya relationship |ν1−ν2|≦20.
 15. The optical imaging lens set of claim 14,wherein a distance TTL between said object-side surface of said firstlens element to an image plane, and a thickness T4 of said fourth lenselement along said optical axis satisfy a relationship TTL/T4≦21.49. 16.The optical imaging lens set of claim 1, wherein a distance TTL betweensaid object-side surface of said first lens element to an image plane,and a distance BFL between the image-side surface of said fourth lenselement to an image plane satisfy a relationship TTL/BFL≦5.77.
 17. Theoptical imaging lens set of claim 16, wherein an Abbe number ν2 of saidsecond lens element, and an Abbe number ν3 of said third lens elementsatisfy a relationship |ν2−ν3|≦10.
 18. The optical imaging lens set ofclaim 1, wherein a total thickness ALT of said first lens element, saidsecond lens element, said third lens element and said fourth lenselement along said optical axis, and the sum of all three air gaps AAGbetween each lens element from said first lens element to said fourthlens element along the optical axis satisfy a relationship ALT/AAG≦9.22.19. The optical imaging lens set of claim 18, wherein a thickness T3 ofsaid third lens element along said optical axis, and a thickness T4 ofsaid fourth lens element along said optical axis satisfy a relationshipT3/T4≦4.34.
 20. An electronic device, comprising: a case; and an imagemodule disposed in said case and comprising: an optical imaging lens setof claim 1; a barrel for the installation of said optical imaging lensset; a module housing unit for the installation of said barrel; asubstrate for the installation of said module housing unit; and an imagesensor disposed on the substrate and disposed at an image side of saidoptical imaging lens set.